953 lines
42 KiB
Rust
953 lines
42 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use llvm::{self, ValueRef};
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use rustc::ty::{self, Ty};
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use rustc::ty::cast::{CastTy, IntTy};
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use rustc::ty::layout::{self, LayoutOf};
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use rustc::mir;
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use rustc::middle::lang_items::ExchangeMallocFnLangItem;
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use rustc_apfloat::{ieee, Float, Status, Round};
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use std::{u128, i128};
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use base;
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use builder::Builder;
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use callee;
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use common::{self, val_ty};
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use common::{C_bool, C_u8, C_i32, C_u32, C_u64, C_undef, C_null, C_usize, C_uint, C_uint_big};
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use consts;
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use monomorphize;
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use type_::Type;
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use type_of::LayoutLlvmExt;
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use value::Value;
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use super::{FunctionCx, LocalRef};
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use super::operand::{OperandRef, OperandValue};
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use super::place::PlaceRef;
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impl<'a, 'tcx> FunctionCx<'a, 'tcx> {
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pub fn codegen_rvalue(&mut self,
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bx: Builder<'a, 'tcx>,
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dest: PlaceRef<'tcx>,
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rvalue: &mir::Rvalue<'tcx>)
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-> Builder<'a, 'tcx>
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{
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debug!("codegen_rvalue(dest.llval={:?}, rvalue={:?})",
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Value(dest.llval), rvalue);
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match *rvalue {
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mir::Rvalue::Use(ref operand) => {
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let cg_operand = self.codegen_operand(&bx, operand);
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// FIXME: consider not copying constants through stack. (fixable by codegenning
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// constants into OperandValue::Ref, why don’t we do that yet if we don’t?)
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cg_operand.val.store(&bx, dest);
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bx
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}
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mir::Rvalue::Cast(mir::CastKind::Unsize, ref source, _) => {
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// The destination necessarily contains a fat pointer, so if
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// it's a scalar pair, it's a fat pointer or newtype thereof.
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if dest.layout.is_llvm_scalar_pair() {
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// into-coerce of a thin pointer to a fat pointer - just
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// use the operand path.
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let (bx, temp) = self.codegen_rvalue_operand(bx, rvalue);
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temp.val.store(&bx, dest);
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return bx;
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}
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// Unsize of a nontrivial struct. I would prefer for
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// this to be eliminated by MIR building, but
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// `CoerceUnsized` can be passed by a where-clause,
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// so the (generic) MIR may not be able to expand it.
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let operand = self.codegen_operand(&bx, source);
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match operand.val {
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OperandValue::Pair(..) |
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OperandValue::Immediate(_) => {
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// unsize from an immediate structure. We don't
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// really need a temporary alloca here, but
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// avoiding it would require us to have
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// `coerce_unsized_into` use extractvalue to
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// index into the struct, and this case isn't
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// important enough for it.
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debug!("codegen_rvalue: creating ugly alloca");
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let scratch = PlaceRef::alloca(&bx, operand.layout, "__unsize_temp");
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scratch.storage_live(&bx);
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operand.val.store(&bx, scratch);
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base::coerce_unsized_into(&bx, scratch, dest);
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scratch.storage_dead(&bx);
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}
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OperandValue::Ref(llref, align) => {
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let source = PlaceRef::new_sized(llref, operand.layout, align);
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base::coerce_unsized_into(&bx, source, dest);
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}
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}
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bx
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}
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mir::Rvalue::Repeat(ref elem, count) => {
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let cg_elem = self.codegen_operand(&bx, elem);
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// Do not generate the loop for zero-sized elements or empty arrays.
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if dest.layout.is_zst() {
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return bx;
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}
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let start = dest.project_index(&bx, C_usize(bx.cx, 0)).llval;
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if let OperandValue::Immediate(v) = cg_elem.val {
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let align = C_i32(bx.cx, dest.align.abi() as i32);
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let size = C_usize(bx.cx, dest.layout.size.bytes());
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// Use llvm.memset.p0i8.* to initialize all zero arrays
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if common::is_const_integral(v) && common::const_to_uint(v) == 0 {
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let fill = C_u8(bx.cx, 0);
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base::call_memset(&bx, start, fill, size, align, false);
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return bx;
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}
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// Use llvm.memset.p0i8.* to initialize byte arrays
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let v = base::from_immediate(&bx, v);
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if common::val_ty(v) == Type::i8(bx.cx) {
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base::call_memset(&bx, start, v, size, align, false);
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return bx;
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}
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}
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let count = C_usize(bx.cx, count);
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let end = dest.project_index(&bx, count).llval;
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let header_bx = bx.build_sibling_block("repeat_loop_header");
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let body_bx = bx.build_sibling_block("repeat_loop_body");
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let next_bx = bx.build_sibling_block("repeat_loop_next");
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bx.br(header_bx.llbb());
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let current = header_bx.phi(common::val_ty(start), &[start], &[bx.llbb()]);
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let keep_going = header_bx.icmp(llvm::IntNE, current, end);
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header_bx.cond_br(keep_going, body_bx.llbb(), next_bx.llbb());
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cg_elem.val.store(&body_bx,
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PlaceRef::new_sized(current, cg_elem.layout, dest.align));
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let next = body_bx.inbounds_gep(current, &[C_usize(bx.cx, 1)]);
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body_bx.br(header_bx.llbb());
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header_bx.add_incoming_to_phi(current, next, body_bx.llbb());
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next_bx
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}
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mir::Rvalue::Aggregate(ref kind, ref operands) => {
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let (dest, active_field_index) = match **kind {
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mir::AggregateKind::Adt(adt_def, variant_index, _, active_field_index) => {
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dest.codegen_set_discr(&bx, variant_index);
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if adt_def.is_enum() {
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(dest.project_downcast(&bx, variant_index), active_field_index)
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} else {
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(dest, active_field_index)
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}
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}
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_ => (dest, None)
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};
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for (i, operand) in operands.iter().enumerate() {
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let op = self.codegen_operand(&bx, operand);
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// Do not generate stores and GEPis for zero-sized fields.
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if !op.layout.is_zst() {
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let field_index = active_field_index.unwrap_or(i);
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op.val.store(&bx, dest.project_field(&bx, field_index));
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}
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}
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bx
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}
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_ => {
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assert!(self.rvalue_creates_operand(rvalue));
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let (bx, temp) = self.codegen_rvalue_operand(bx, rvalue);
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temp.val.store(&bx, dest);
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bx
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}
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}
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}
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pub fn codegen_rvalue_operand(&mut self,
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bx: Builder<'a, 'tcx>,
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rvalue: &mir::Rvalue<'tcx>)
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-> (Builder<'a, 'tcx>, OperandRef<'tcx>)
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{
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assert!(self.rvalue_creates_operand(rvalue), "cannot codegen {:?} to operand", rvalue);
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match *rvalue {
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mir::Rvalue::Cast(ref kind, ref source, mir_cast_ty) => {
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let operand = self.codegen_operand(&bx, source);
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debug!("cast operand is {:?}", operand);
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let cast = bx.cx.layout_of(self.monomorphize(&mir_cast_ty));
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let val = match *kind {
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mir::CastKind::ReifyFnPointer => {
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match operand.layout.ty.sty {
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ty::TyFnDef(def_id, substs) => {
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if bx.cx.tcx.has_attr(def_id, "rustc_args_required_const") {
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bug!("reifying a fn ptr that requires \
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const arguments");
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}
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OperandValue::Immediate(
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callee::resolve_and_get_fn(bx.cx, def_id, substs))
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}
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_ => {
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bug!("{} cannot be reified to a fn ptr", operand.layout.ty)
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}
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}
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}
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mir::CastKind::ClosureFnPointer => {
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match operand.layout.ty.sty {
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ty::TyClosure(def_id, substs) => {
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let instance = monomorphize::resolve_closure(
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bx.cx.tcx, def_id, substs, ty::ClosureKind::FnOnce);
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OperandValue::Immediate(callee::get_fn(bx.cx, instance))
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}
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_ => {
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bug!("{} cannot be cast to a fn ptr", operand.layout.ty)
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}
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}
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}
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mir::CastKind::UnsafeFnPointer => {
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// this is a no-op at the LLVM level
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operand.val
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}
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mir::CastKind::Unsize => {
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assert!(cast.is_llvm_scalar_pair());
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match operand.val {
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OperandValue::Pair(lldata, llextra) => {
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// unsize from a fat pointer - this is a
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// "trait-object-to-supertrait" coercion, for
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// example,
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// &'a fmt::Debug+Send => &'a fmt::Debug,
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// HACK(eddyb) have to bitcast pointers
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// until LLVM removes pointee types.
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let lldata = bx.pointercast(lldata,
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cast.scalar_pair_element_llvm_type(bx.cx, 0));
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OperandValue::Pair(lldata, llextra)
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}
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OperandValue::Immediate(lldata) => {
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// "standard" unsize
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let (lldata, llextra) = base::unsize_thin_ptr(&bx, lldata,
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operand.layout.ty, cast.ty);
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OperandValue::Pair(lldata, llextra)
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}
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OperandValue::Ref(..) => {
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bug!("by-ref operand {:?} in codegen_rvalue_operand",
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operand);
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}
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}
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}
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mir::CastKind::Misc if operand.layout.is_llvm_scalar_pair() => {
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if let OperandValue::Pair(data_ptr, meta) = operand.val {
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if cast.is_llvm_scalar_pair() {
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let data_cast = bx.pointercast(data_ptr,
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cast.scalar_pair_element_llvm_type(bx.cx, 0));
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OperandValue::Pair(data_cast, meta)
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} else { // cast to thin-ptr
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// Cast of fat-ptr to thin-ptr is an extraction of data-ptr and
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// pointer-cast of that pointer to desired pointer type.
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let llcast_ty = cast.immediate_llvm_type(bx.cx);
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let llval = bx.pointercast(data_ptr, llcast_ty);
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OperandValue::Immediate(llval)
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}
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} else {
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bug!("Unexpected non-Pair operand")
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}
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}
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mir::CastKind::Misc => {
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assert!(cast.is_llvm_immediate());
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let ll_t_out = cast.immediate_llvm_type(bx.cx);
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if operand.layout.abi == layout::Abi::Uninhabited {
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return (bx, OperandRef {
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val: OperandValue::Immediate(C_undef(ll_t_out)),
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layout: cast,
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});
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}
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let r_t_in = CastTy::from_ty(operand.layout.ty)
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.expect("bad input type for cast");
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let r_t_out = CastTy::from_ty(cast.ty).expect("bad output type for cast");
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let ll_t_in = operand.layout.immediate_llvm_type(bx.cx);
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match operand.layout.variants {
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layout::Variants::Single { index } => {
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if let Some(def) = operand.layout.ty.ty_adt_def() {
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let discr_val = def
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.discriminant_for_variant(bx.cx.tcx, index)
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.val;
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let discr = C_uint_big(ll_t_out, discr_val);
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return (bx, OperandRef {
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val: OperandValue::Immediate(discr),
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layout: cast,
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});
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}
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}
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layout::Variants::Tagged { .. } |
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layout::Variants::NicheFilling { .. } => {},
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}
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let llval = operand.immediate();
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let mut signed = false;
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if let layout::Abi::Scalar(ref scalar) = operand.layout.abi {
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if let layout::Int(_, s) = scalar.value {
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signed = s;
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if scalar.valid_range.end() > scalar.valid_range.start() {
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// We want `table[e as usize]` to not
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// have bound checks, and this is the most
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// convenient place to put the `assume`.
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base::call_assume(&bx, bx.icmp(
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llvm::IntULE,
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llval,
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C_uint_big(ll_t_in, *scalar.valid_range.end())
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));
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}
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}
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}
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let newval = match (r_t_in, r_t_out) {
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(CastTy::Int(_), CastTy::Int(_)) => {
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bx.intcast(llval, ll_t_out, signed)
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}
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(CastTy::Float, CastTy::Float) => {
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let srcsz = ll_t_in.float_width();
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let dstsz = ll_t_out.float_width();
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if dstsz > srcsz {
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bx.fpext(llval, ll_t_out)
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} else if srcsz > dstsz {
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bx.fptrunc(llval, ll_t_out)
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} else {
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llval
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}
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}
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(CastTy::Ptr(_), CastTy::Ptr(_)) |
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(CastTy::FnPtr, CastTy::Ptr(_)) |
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(CastTy::RPtr(_), CastTy::Ptr(_)) =>
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bx.pointercast(llval, ll_t_out),
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(CastTy::Ptr(_), CastTy::Int(_)) |
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(CastTy::FnPtr, CastTy::Int(_)) =>
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bx.ptrtoint(llval, ll_t_out),
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(CastTy::Int(_), CastTy::Ptr(_)) => {
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let usize_llval = bx.intcast(llval, bx.cx.isize_ty, signed);
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bx.inttoptr(usize_llval, ll_t_out)
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}
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(CastTy::Int(_), CastTy::Float) =>
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cast_int_to_float(&bx, signed, llval, ll_t_in, ll_t_out),
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(CastTy::Float, CastTy::Int(IntTy::I)) =>
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cast_float_to_int(&bx, true, llval, ll_t_in, ll_t_out),
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(CastTy::Float, CastTy::Int(_)) =>
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cast_float_to_int(&bx, false, llval, ll_t_in, ll_t_out),
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_ => bug!("unsupported cast: {:?} to {:?}", operand.layout.ty, cast.ty)
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};
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OperandValue::Immediate(newval)
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}
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};
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(bx, OperandRef {
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val,
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layout: cast
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})
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}
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mir::Rvalue::Ref(_, bk, ref place) => {
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let cg_place = self.codegen_place(&bx, place);
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let ty = cg_place.layout.ty;
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// Note: places are indirect, so storing the `llval` into the
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// destination effectively creates a reference.
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let val = if !bx.cx.type_has_metadata(ty) {
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OperandValue::Immediate(cg_place.llval)
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} else {
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OperandValue::Pair(cg_place.llval, cg_place.llextra)
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};
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(bx, OperandRef {
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val,
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layout: self.cx.layout_of(self.cx.tcx.mk_ref(
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self.cx.tcx.types.re_erased,
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ty::TypeAndMut { ty, mutbl: bk.to_mutbl_lossy() }
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)),
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})
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}
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mir::Rvalue::Len(ref place) => {
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let size = self.evaluate_array_len(&bx, place);
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let operand = OperandRef {
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val: OperandValue::Immediate(size),
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layout: bx.cx.layout_of(bx.tcx().types.usize),
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};
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(bx, operand)
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}
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mir::Rvalue::BinaryOp(op, ref lhs, ref rhs) => {
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let lhs = self.codegen_operand(&bx, lhs);
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let rhs = self.codegen_operand(&bx, rhs);
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let llresult = match (lhs.val, rhs.val) {
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(OperandValue::Pair(lhs_addr, lhs_extra),
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OperandValue::Pair(rhs_addr, rhs_extra)) => {
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self.codegen_fat_ptr_binop(&bx, op,
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lhs_addr, lhs_extra,
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rhs_addr, rhs_extra,
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lhs.layout.ty)
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}
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(OperandValue::Immediate(lhs_val),
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OperandValue::Immediate(rhs_val)) => {
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self.codegen_scalar_binop(&bx, op, lhs_val, rhs_val, lhs.layout.ty)
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}
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_ => bug!()
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};
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let operand = OperandRef {
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val: OperandValue::Immediate(llresult),
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layout: bx.cx.layout_of(
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op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty)),
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};
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(bx, operand)
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}
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mir::Rvalue::CheckedBinaryOp(op, ref lhs, ref rhs) => {
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let lhs = self.codegen_operand(&bx, lhs);
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let rhs = self.codegen_operand(&bx, rhs);
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let result = self.codegen_scalar_checked_binop(&bx, op,
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lhs.immediate(), rhs.immediate(),
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lhs.layout.ty);
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let val_ty = op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty);
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let operand_ty = bx.tcx().intern_tup(&[val_ty, bx.tcx().types.bool]);
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let operand = OperandRef {
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val: result,
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layout: bx.cx.layout_of(operand_ty)
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};
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(bx, operand)
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}
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mir::Rvalue::UnaryOp(op, ref operand) => {
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let operand = self.codegen_operand(&bx, operand);
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let lloperand = operand.immediate();
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let is_float = operand.layout.ty.is_fp();
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let llval = match op {
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mir::UnOp::Not => bx.not(lloperand),
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mir::UnOp::Neg => if is_float {
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bx.fneg(lloperand)
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} else {
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bx.neg(lloperand)
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}
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};
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(bx, OperandRef {
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val: OperandValue::Immediate(llval),
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layout: operand.layout,
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})
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}
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mir::Rvalue::Discriminant(ref place) => {
|
||
let discr_ty = rvalue.ty(&*self.mir, bx.tcx());
|
||
let discr = self.codegen_place(&bx, place)
|
||
.codegen_get_discr(&bx, discr_ty);
|
||
(bx, OperandRef {
|
||
val: OperandValue::Immediate(discr),
|
||
layout: self.cx.layout_of(discr_ty)
|
||
})
|
||
}
|
||
|
||
mir::Rvalue::NullaryOp(mir::NullOp::SizeOf, ty) => {
|
||
assert!(bx.cx.type_is_sized(ty));
|
||
let val = C_usize(bx.cx, bx.cx.size_of(ty).bytes());
|
||
let tcx = bx.tcx();
|
||
(bx, OperandRef {
|
||
val: OperandValue::Immediate(val),
|
||
layout: self.cx.layout_of(tcx.types.usize),
|
||
})
|
||
}
|
||
|
||
mir::Rvalue::NullaryOp(mir::NullOp::Box, content_ty) => {
|
||
let content_ty: Ty<'tcx> = self.monomorphize(&content_ty);
|
||
let (size, align) = bx.cx.size_and_align_of(content_ty);
|
||
let llsize = C_usize(bx.cx, size.bytes());
|
||
let llalign = C_usize(bx.cx, align.abi());
|
||
let box_layout = bx.cx.layout_of(bx.tcx().mk_box(content_ty));
|
||
let llty_ptr = box_layout.llvm_type(bx.cx);
|
||
|
||
// Allocate space:
|
||
let def_id = match bx.tcx().lang_items().require(ExchangeMallocFnLangItem) {
|
||
Ok(id) => id,
|
||
Err(s) => {
|
||
bx.sess().fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
|
||
}
|
||
};
|
||
let instance = ty::Instance::mono(bx.tcx(), def_id);
|
||
let r = callee::get_fn(bx.cx, instance);
|
||
let val = bx.pointercast(bx.call(r, &[llsize, llalign], None), llty_ptr);
|
||
|
||
let operand = OperandRef {
|
||
val: OperandValue::Immediate(val),
|
||
layout: box_layout,
|
||
};
|
||
(bx, operand)
|
||
}
|
||
mir::Rvalue::Use(ref operand) => {
|
||
let operand = self.codegen_operand(&bx, operand);
|
||
(bx, operand)
|
||
}
|
||
mir::Rvalue::Repeat(..) |
|
||
mir::Rvalue::Aggregate(..) => {
|
||
// According to `rvalue_creates_operand`, only ZST
|
||
// aggregate rvalues are allowed to be operands.
|
||
let ty = rvalue.ty(self.mir, self.cx.tcx);
|
||
(bx, OperandRef::new_zst(self.cx,
|
||
self.cx.layout_of(self.monomorphize(&ty))))
|
||
}
|
||
}
|
||
}
|
||
|
||
fn evaluate_array_len(&mut self,
|
||
bx: &Builder<'a, 'tcx>,
|
||
place: &mir::Place<'tcx>) -> ValueRef
|
||
{
|
||
// ZST are passed as operands and require special handling
|
||
// because codegen_place() panics if Local is operand.
|
||
if let mir::Place::Local(index) = *place {
|
||
if let LocalRef::Operand(Some(op)) = self.locals[index] {
|
||
if let ty::TyArray(_, n) = op.layout.ty.sty {
|
||
let n = n.unwrap_usize(bx.cx.tcx);
|
||
return common::C_usize(bx.cx, n);
|
||
}
|
||
}
|
||
}
|
||
// use common size calculation for non zero-sized types
|
||
let cg_value = self.codegen_place(&bx, place);
|
||
return cg_value.len(bx.cx);
|
||
}
|
||
|
||
pub fn codegen_scalar_binop(&mut self,
|
||
bx: &Builder<'a, 'tcx>,
|
||
op: mir::BinOp,
|
||
lhs: ValueRef,
|
||
rhs: ValueRef,
|
||
input_ty: Ty<'tcx>) -> ValueRef {
|
||
let is_float = input_ty.is_fp();
|
||
let is_signed = input_ty.is_signed();
|
||
let is_nil = input_ty.is_nil();
|
||
match op {
|
||
mir::BinOp::Add => if is_float {
|
||
bx.fadd(lhs, rhs)
|
||
} else {
|
||
bx.add(lhs, rhs)
|
||
},
|
||
mir::BinOp::Sub => if is_float {
|
||
bx.fsub(lhs, rhs)
|
||
} else {
|
||
bx.sub(lhs, rhs)
|
||
},
|
||
mir::BinOp::Mul => if is_float {
|
||
bx.fmul(lhs, rhs)
|
||
} else {
|
||
bx.mul(lhs, rhs)
|
||
},
|
||
mir::BinOp::Div => if is_float {
|
||
bx.fdiv(lhs, rhs)
|
||
} else if is_signed {
|
||
bx.sdiv(lhs, rhs)
|
||
} else {
|
||
bx.udiv(lhs, rhs)
|
||
},
|
||
mir::BinOp::Rem => if is_float {
|
||
bx.frem(lhs, rhs)
|
||
} else if is_signed {
|
||
bx.srem(lhs, rhs)
|
||
} else {
|
||
bx.urem(lhs, rhs)
|
||
},
|
||
mir::BinOp::BitOr => bx.or(lhs, rhs),
|
||
mir::BinOp::BitAnd => bx.and(lhs, rhs),
|
||
mir::BinOp::BitXor => bx.xor(lhs, rhs),
|
||
mir::BinOp::Offset => bx.inbounds_gep(lhs, &[rhs]),
|
||
mir::BinOp::Shl => common::build_unchecked_lshift(bx, lhs, rhs),
|
||
mir::BinOp::Shr => common::build_unchecked_rshift(bx, input_ty, lhs, rhs),
|
||
mir::BinOp::Ne | mir::BinOp::Lt | mir::BinOp::Gt |
|
||
mir::BinOp::Eq | mir::BinOp::Le | mir::BinOp::Ge => if is_nil {
|
||
C_bool(bx.cx, match op {
|
||
mir::BinOp::Ne | mir::BinOp::Lt | mir::BinOp::Gt => false,
|
||
mir::BinOp::Eq | mir::BinOp::Le | mir::BinOp::Ge => true,
|
||
_ => unreachable!()
|
||
})
|
||
} else if is_float {
|
||
bx.fcmp(
|
||
base::bin_op_to_fcmp_predicate(op.to_hir_binop()),
|
||
lhs, rhs
|
||
)
|
||
} else {
|
||
bx.icmp(
|
||
base::bin_op_to_icmp_predicate(op.to_hir_binop(), is_signed),
|
||
lhs, rhs
|
||
)
|
||
}
|
||
}
|
||
}
|
||
|
||
pub fn codegen_fat_ptr_binop(&mut self,
|
||
bx: &Builder<'a, 'tcx>,
|
||
op: mir::BinOp,
|
||
lhs_addr: ValueRef,
|
||
lhs_extra: ValueRef,
|
||
rhs_addr: ValueRef,
|
||
rhs_extra: ValueRef,
|
||
_input_ty: Ty<'tcx>)
|
||
-> ValueRef {
|
||
match op {
|
||
mir::BinOp::Eq => {
|
||
bx.and(
|
||
bx.icmp(llvm::IntEQ, lhs_addr, rhs_addr),
|
||
bx.icmp(llvm::IntEQ, lhs_extra, rhs_extra)
|
||
)
|
||
}
|
||
mir::BinOp::Ne => {
|
||
bx.or(
|
||
bx.icmp(llvm::IntNE, lhs_addr, rhs_addr),
|
||
bx.icmp(llvm::IntNE, lhs_extra, rhs_extra)
|
||
)
|
||
}
|
||
mir::BinOp::Le | mir::BinOp::Lt |
|
||
mir::BinOp::Ge | mir::BinOp::Gt => {
|
||
// a OP b ~ a.0 STRICT(OP) b.0 | (a.0 == b.0 && a.1 OP a.1)
|
||
let (op, strict_op) = match op {
|
||
mir::BinOp::Lt => (llvm::IntULT, llvm::IntULT),
|
||
mir::BinOp::Le => (llvm::IntULE, llvm::IntULT),
|
||
mir::BinOp::Gt => (llvm::IntUGT, llvm::IntUGT),
|
||
mir::BinOp::Ge => (llvm::IntUGE, llvm::IntUGT),
|
||
_ => bug!(),
|
||
};
|
||
|
||
bx.or(
|
||
bx.icmp(strict_op, lhs_addr, rhs_addr),
|
||
bx.and(
|
||
bx.icmp(llvm::IntEQ, lhs_addr, rhs_addr),
|
||
bx.icmp(op, lhs_extra, rhs_extra)
|
||
)
|
||
)
|
||
}
|
||
_ => {
|
||
bug!("unexpected fat ptr binop");
|
||
}
|
||
}
|
||
}
|
||
|
||
pub fn codegen_scalar_checked_binop(&mut self,
|
||
bx: &Builder<'a, 'tcx>,
|
||
op: mir::BinOp,
|
||
lhs: ValueRef,
|
||
rhs: ValueRef,
|
||
input_ty: Ty<'tcx>) -> OperandValue {
|
||
// This case can currently arise only from functions marked
|
||
// with #[rustc_inherit_overflow_checks] and inlined from
|
||
// another crate (mostly core::num generic/#[inline] fns),
|
||
// while the current crate doesn't use overflow checks.
|
||
if !bx.cx.check_overflow {
|
||
let val = self.codegen_scalar_binop(bx, op, lhs, rhs, input_ty);
|
||
return OperandValue::Pair(val, C_bool(bx.cx, false));
|
||
}
|
||
|
||
let (val, of) = match op {
|
||
// These are checked using intrinsics
|
||
mir::BinOp::Add | mir::BinOp::Sub | mir::BinOp::Mul => {
|
||
let oop = match op {
|
||
mir::BinOp::Add => OverflowOp::Add,
|
||
mir::BinOp::Sub => OverflowOp::Sub,
|
||
mir::BinOp::Mul => OverflowOp::Mul,
|
||
_ => unreachable!()
|
||
};
|
||
let intrinsic = get_overflow_intrinsic(oop, bx, input_ty);
|
||
let res = bx.call(intrinsic, &[lhs, rhs], None);
|
||
|
||
(bx.extract_value(res, 0),
|
||
bx.extract_value(res, 1))
|
||
}
|
||
mir::BinOp::Shl | mir::BinOp::Shr => {
|
||
let lhs_llty = val_ty(lhs);
|
||
let rhs_llty = val_ty(rhs);
|
||
let invert_mask = common::shift_mask_val(&bx, lhs_llty, rhs_llty, true);
|
||
let outer_bits = bx.and(rhs, invert_mask);
|
||
|
||
let of = bx.icmp(llvm::IntNE, outer_bits, C_null(rhs_llty));
|
||
let val = self.codegen_scalar_binop(bx, op, lhs, rhs, input_ty);
|
||
|
||
(val, of)
|
||
}
|
||
_ => {
|
||
bug!("Operator `{:?}` is not a checkable operator", op)
|
||
}
|
||
};
|
||
|
||
OperandValue::Pair(val, of)
|
||
}
|
||
|
||
pub fn rvalue_creates_operand(&self, rvalue: &mir::Rvalue<'tcx>) -> bool {
|
||
match *rvalue {
|
||
mir::Rvalue::Ref(..) |
|
||
mir::Rvalue::Len(..) |
|
||
mir::Rvalue::Cast(..) | // (*)
|
||
mir::Rvalue::BinaryOp(..) |
|
||
mir::Rvalue::CheckedBinaryOp(..) |
|
||
mir::Rvalue::UnaryOp(..) |
|
||
mir::Rvalue::Discriminant(..) |
|
||
mir::Rvalue::NullaryOp(..) |
|
||
mir::Rvalue::Use(..) => // (*)
|
||
true,
|
||
mir::Rvalue::Repeat(..) |
|
||
mir::Rvalue::Aggregate(..) => {
|
||
let ty = rvalue.ty(self.mir, self.cx.tcx);
|
||
let ty = self.monomorphize(&ty);
|
||
self.cx.layout_of(ty).is_zst()
|
||
}
|
||
}
|
||
|
||
// (*) this is only true if the type is suitable
|
||
}
|
||
}
|
||
|
||
#[derive(Copy, Clone)]
|
||
enum OverflowOp {
|
||
Add, Sub, Mul
|
||
}
|
||
|
||
fn get_overflow_intrinsic(oop: OverflowOp, bx: &Builder, ty: Ty) -> ValueRef {
|
||
use syntax::ast::IntTy::*;
|
||
use syntax::ast::UintTy::*;
|
||
use rustc::ty::{TyInt, TyUint};
|
||
|
||
let tcx = bx.tcx();
|
||
|
||
let new_sty = match ty.sty {
|
||
TyInt(Isize) => match &tcx.sess.target.target.target_pointer_width[..] {
|
||
"16" => TyInt(I16),
|
||
"32" => TyInt(I32),
|
||
"64" => TyInt(I64),
|
||
_ => panic!("unsupported target word size")
|
||
},
|
||
TyUint(Usize) => match &tcx.sess.target.target.target_pointer_width[..] {
|
||
"16" => TyUint(U16),
|
||
"32" => TyUint(U32),
|
||
"64" => TyUint(U64),
|
||
_ => panic!("unsupported target word size")
|
||
},
|
||
ref t @ TyUint(_) | ref t @ TyInt(_) => t.clone(),
|
||
_ => panic!("tried to get overflow intrinsic for op applied to non-int type")
|
||
};
|
||
|
||
let name = match oop {
|
||
OverflowOp::Add => match new_sty {
|
||
TyInt(I8) => "llvm.sadd.with.overflow.i8",
|
||
TyInt(I16) => "llvm.sadd.with.overflow.i16",
|
||
TyInt(I32) => "llvm.sadd.with.overflow.i32",
|
||
TyInt(I64) => "llvm.sadd.with.overflow.i64",
|
||
TyInt(I128) => "llvm.sadd.with.overflow.i128",
|
||
|
||
TyUint(U8) => "llvm.uadd.with.overflow.i8",
|
||
TyUint(U16) => "llvm.uadd.with.overflow.i16",
|
||
TyUint(U32) => "llvm.uadd.with.overflow.i32",
|
||
TyUint(U64) => "llvm.uadd.with.overflow.i64",
|
||
TyUint(U128) => "llvm.uadd.with.overflow.i128",
|
||
|
||
_ => unreachable!(),
|
||
},
|
||
OverflowOp::Sub => match new_sty {
|
||
TyInt(I8) => "llvm.ssub.with.overflow.i8",
|
||
TyInt(I16) => "llvm.ssub.with.overflow.i16",
|
||
TyInt(I32) => "llvm.ssub.with.overflow.i32",
|
||
TyInt(I64) => "llvm.ssub.with.overflow.i64",
|
||
TyInt(I128) => "llvm.ssub.with.overflow.i128",
|
||
|
||
TyUint(U8) => "llvm.usub.with.overflow.i8",
|
||
TyUint(U16) => "llvm.usub.with.overflow.i16",
|
||
TyUint(U32) => "llvm.usub.with.overflow.i32",
|
||
TyUint(U64) => "llvm.usub.with.overflow.i64",
|
||
TyUint(U128) => "llvm.usub.with.overflow.i128",
|
||
|
||
_ => unreachable!(),
|
||
},
|
||
OverflowOp::Mul => match new_sty {
|
||
TyInt(I8) => "llvm.smul.with.overflow.i8",
|
||
TyInt(I16) => "llvm.smul.with.overflow.i16",
|
||
TyInt(I32) => "llvm.smul.with.overflow.i32",
|
||
TyInt(I64) => "llvm.smul.with.overflow.i64",
|
||
TyInt(I128) => "llvm.smul.with.overflow.i128",
|
||
|
||
TyUint(U8) => "llvm.umul.with.overflow.i8",
|
||
TyUint(U16) => "llvm.umul.with.overflow.i16",
|
||
TyUint(U32) => "llvm.umul.with.overflow.i32",
|
||
TyUint(U64) => "llvm.umul.with.overflow.i64",
|
||
TyUint(U128) => "llvm.umul.with.overflow.i128",
|
||
|
||
_ => unreachable!(),
|
||
},
|
||
};
|
||
|
||
bx.cx.get_intrinsic(&name)
|
||
}
|
||
|
||
fn cast_int_to_float(bx: &Builder,
|
||
signed: bool,
|
||
x: ValueRef,
|
||
int_ty: Type,
|
||
float_ty: Type) -> ValueRef {
|
||
// Most integer types, even i128, fit into [-f32::MAX, f32::MAX] after rounding.
|
||
// It's only u128 -> f32 that can cause overflows (i.e., should yield infinity).
|
||
// LLVM's uitofp produces undef in those cases, so we manually check for that case.
|
||
let is_u128_to_f32 = !signed && int_ty.int_width() == 128 && float_ty.float_width() == 32;
|
||
if is_u128_to_f32 {
|
||
// All inputs greater or equal to (f32::MAX + 0.5 ULP) are rounded to infinity,
|
||
// and for everything else LLVM's uitofp works just fine.
|
||
use rustc_apfloat::ieee::Single;
|
||
use rustc_apfloat::Float;
|
||
const MAX_F32_PLUS_HALF_ULP: u128 = ((1 << (Single::PRECISION + 1)) - 1)
|
||
<< (Single::MAX_EXP - Single::PRECISION as i16);
|
||
let max = C_uint_big(int_ty, MAX_F32_PLUS_HALF_ULP);
|
||
let overflow = bx.icmp(llvm::IntUGE, x, max);
|
||
let infinity_bits = C_u32(bx.cx, ieee::Single::INFINITY.to_bits() as u32);
|
||
let infinity = consts::bitcast(infinity_bits, float_ty);
|
||
bx.select(overflow, infinity, bx.uitofp(x, float_ty))
|
||
} else {
|
||
if signed {
|
||
bx.sitofp(x, float_ty)
|
||
} else {
|
||
bx.uitofp(x, float_ty)
|
||
}
|
||
}
|
||
}
|
||
|
||
fn cast_float_to_int(bx: &Builder,
|
||
signed: bool,
|
||
x: ValueRef,
|
||
float_ty: Type,
|
||
int_ty: Type) -> ValueRef {
|
||
let fptosui_result = if signed {
|
||
bx.fptosi(x, int_ty)
|
||
} else {
|
||
bx.fptoui(x, int_ty)
|
||
};
|
||
|
||
if !bx.sess().opts.debugging_opts.saturating_float_casts {
|
||
return fptosui_result;
|
||
}
|
||
// LLVM's fpto[su]i returns undef when the input x is infinite, NaN, or does not fit into the
|
||
// destination integer type after rounding towards zero. This `undef` value can cause UB in
|
||
// safe code (see issue #10184), so we implement a saturating conversion on top of it:
|
||
// Semantically, the mathematical value of the input is rounded towards zero to the next
|
||
// mathematical integer, and then the result is clamped into the range of the destination
|
||
// integer type. Positive and negative infinity are mapped to the maximum and minimum value of
|
||
// the destination integer type. NaN is mapped to 0.
|
||
//
|
||
// Define f_min and f_max as the largest and smallest (finite) floats that are exactly equal to
|
||
// a value representable in int_ty.
|
||
// They are exactly equal to int_ty::{MIN,MAX} if float_ty has enough significand bits.
|
||
// Otherwise, int_ty::MAX must be rounded towards zero, as it is one less than a power of two.
|
||
// int_ty::MIN, however, is either zero or a negative power of two and is thus exactly
|
||
// representable. Note that this only works if float_ty's exponent range is sufficiently large.
|
||
// f16 or 256 bit integers would break this property. Right now the smallest float type is f32
|
||
// with exponents ranging up to 127, which is barely enough for i128::MIN = -2^127.
|
||
// On the other hand, f_max works even if int_ty::MAX is greater than float_ty::MAX. Because
|
||
// we're rounding towards zero, we just get float_ty::MAX (which is always an integer).
|
||
// This already happens today with u128::MAX = 2^128 - 1 > f32::MAX.
|
||
fn compute_clamp_bounds<F: Float>(signed: bool, int_ty: Type) -> (u128, u128) {
|
||
let rounded_min = F::from_i128_r(int_min(signed, int_ty), Round::TowardZero);
|
||
assert_eq!(rounded_min.status, Status::OK);
|
||
let rounded_max = F::from_u128_r(int_max(signed, int_ty), Round::TowardZero);
|
||
assert!(rounded_max.value.is_finite());
|
||
(rounded_min.value.to_bits(), rounded_max.value.to_bits())
|
||
}
|
||
fn int_max(signed: bool, int_ty: Type) -> u128 {
|
||
let shift_amount = 128 - int_ty.int_width();
|
||
if signed {
|
||
i128::MAX as u128 >> shift_amount
|
||
} else {
|
||
u128::MAX >> shift_amount
|
||
}
|
||
}
|
||
fn int_min(signed: bool, int_ty: Type) -> i128 {
|
||
if signed {
|
||
i128::MIN >> (128 - int_ty.int_width())
|
||
} else {
|
||
0
|
||
}
|
||
}
|
||
let float_bits_to_llval = |bits| {
|
||
let bits_llval = match float_ty.float_width() {
|
||
32 => C_u32(bx.cx, bits as u32),
|
||
64 => C_u64(bx.cx, bits as u64),
|
||
n => bug!("unsupported float width {}", n),
|
||
};
|
||
consts::bitcast(bits_llval, float_ty)
|
||
};
|
||
let (f_min, f_max) = match float_ty.float_width() {
|
||
32 => compute_clamp_bounds::<ieee::Single>(signed, int_ty),
|
||
64 => compute_clamp_bounds::<ieee::Double>(signed, int_ty),
|
||
n => bug!("unsupported float width {}", n),
|
||
};
|
||
let f_min = float_bits_to_llval(f_min);
|
||
let f_max = float_bits_to_llval(f_max);
|
||
// To implement saturation, we perform the following steps:
|
||
//
|
||
// 1. Cast x to an integer with fpto[su]i. This may result in undef.
|
||
// 2. Compare x to f_min and f_max, and use the comparison results to select:
|
||
// a) int_ty::MIN if x < f_min or x is NaN
|
||
// b) int_ty::MAX if x > f_max
|
||
// c) the result of fpto[su]i otherwise
|
||
// 3. If x is NaN, return 0.0, otherwise return the result of step 2.
|
||
//
|
||
// This avoids resulting undef because values in range [f_min, f_max] by definition fit into the
|
||
// destination type. It creates an undef temporary, but *producing* undef is not UB. Our use of
|
||
// undef does not introduce any non-determinism either.
|
||
// More importantly, the above procedure correctly implements saturating conversion.
|
||
// Proof (sketch):
|
||
// If x is NaN, 0 is returned by definition.
|
||
// Otherwise, x is finite or infinite and thus can be compared with f_min and f_max.
|
||
// This yields three cases to consider:
|
||
// (1) if x in [f_min, f_max], the result of fpto[su]i is returned, which agrees with
|
||
// saturating conversion for inputs in that range.
|
||
// (2) if x > f_max, then x is larger than int_ty::MAX. This holds even if f_max is rounded
|
||
// (i.e., if f_max < int_ty::MAX) because in those cases, nextUp(f_max) is already larger
|
||
// than int_ty::MAX. Because x is larger than int_ty::MAX, the return value of int_ty::MAX
|
||
// is correct.
|
||
// (3) if x < f_min, then x is smaller than int_ty::MIN. As shown earlier, f_min exactly equals
|
||
// int_ty::MIN and therefore the return value of int_ty::MIN is correct.
|
||
// QED.
|
||
|
||
// Step 1 was already performed above.
|
||
|
||
// Step 2: We use two comparisons and two selects, with %s1 being the result:
|
||
// %less_or_nan = fcmp ult %x, %f_min
|
||
// %greater = fcmp olt %x, %f_max
|
||
// %s0 = select %less_or_nan, int_ty::MIN, %fptosi_result
|
||
// %s1 = select %greater, int_ty::MAX, %s0
|
||
// Note that %less_or_nan uses an *unordered* comparison. This comparison is true if the
|
||
// operands are not comparable (i.e., if x is NaN). The unordered comparison ensures that s1
|
||
// becomes int_ty::MIN if x is NaN.
|
||
// Performance note: Unordered comparison can be lowered to a "flipped" comparison and a
|
||
// negation, and the negation can be merged into the select. Therefore, it not necessarily any
|
||
// more expensive than a ordered ("normal") comparison. Whether these optimizations will be
|
||
// performed is ultimately up to the backend, but at least x86 does perform them.
|
||
let less_or_nan = bx.fcmp(llvm::RealULT, x, f_min);
|
||
let greater = bx.fcmp(llvm::RealOGT, x, f_max);
|
||
let int_max = C_uint_big(int_ty, int_max(signed, int_ty));
|
||
let int_min = C_uint_big(int_ty, int_min(signed, int_ty) as u128);
|
||
let s0 = bx.select(less_or_nan, int_min, fptosui_result);
|
||
let s1 = bx.select(greater, int_max, s0);
|
||
|
||
// Step 3: NaN replacement.
|
||
// For unsigned types, the above step already yielded int_ty::MIN == 0 if x is NaN.
|
||
// Therefore we only need to execute this step for signed integer types.
|
||
if signed {
|
||
// LLVM has no isNaN predicate, so we use (x == x) instead
|
||
bx.select(bx.fcmp(llvm::RealOEQ, x, x), s1, C_uint(int_ty, 0))
|
||
} else {
|
||
s1
|
||
}
|
||
}
|